Novel furan and thiophene compounds



United States Patent 3,331,854 NOVEL FURAN AND THIOPHENE COMPOUNDS Kenneth Robert Huffman and Edwin Fisher Ullman, Stamford, Conn., assignors to American Cyanamid' Company, Stamford, Conn., a corporation of Maine No Drawing. Filed Dec. 14, 1964, Ser. No. 418,336 9 Claims. (Cl. 260-3305) ABSTRACT OF THE DISCLOSURE Benzofuran and thiophene compounds of the formula:

0 i k-R1 wherein Q is oxygen or sulfur, R and R are phenyl or mono-substituted phenyl, and Y typically is hydrogen. The compounds are useful in preparing photochromic cyclohexadiene compounds by reaction with tetracyanoethylene in basic medium.

This invention relates to novel benzofuran and thiophene compounds and to processes for preparing the same.

More particularly, this invention relates to novel comwherein Q is selected from the group consisting of oxygen and sulfur and R and R are selected from the group consisting of phenyl and substituted phenyl, said substituents for phenyl being selected from the group consisting of lower alkyl, lower alkyl thio, cyano, nitro, di(lower alkyl) amino, halogen and trifluoromethyl, and Y is selected from the group consisting of hydrogen, hydroxy, lower alkyl, trifluoromethyl, lower alkoxy, lower alkyl thio, cyano, nitro, halogen, di(lower alkyl)amino, phenyl and lower alkyl-su bstituted phenyl. In the above formula R and R may be the same or different.

Compounds represented by generic Formula I above are prepared by the condensation of benzo[b]thiophenes or benzo[b]furans with the appropriate aroyl derivative in the presence of a Friedel-Crafts type catalyst as follows:

H Y i I R OX catalyst Q I 3,331,854 Patented July 18, 1967 radical which does not become a portion of product (I).

The reactants are known materials. As typical may be mentioned the preparation of 2-benzylbenzo[b]furan by the method of M. Bisogni et al., J. Chem. Soc., 3693 (1955), and the preparation of 2-benzylbenzo[b]thiophene by the method of Royer et al., Bull. Soc. Chim. [5], 28 1534 (1961).

Compounds of Formula I are conveniently prepared by mixing the starting furan or thiophene with the aroyl derivative and thereafter adding the catalyst, preferably in portions over several minutes, e.g., 2 to 10 minutes. The reactants are employed in substantially equimolecular amounts and the catalyst in amounts suflicient to effect catalytic action. Preferably, the catalyst will also be employed in equimolecular amounts with the starting compounds. No particular advantage is gained by varying the quantities of starting compounds or catalyst although substantially less or greater amounts than equimolecular proportions may be employed, if desired, for control of the rate of reaction and yield.

The reaction is preferably conducted in an inert organic solvent medium; however, in those cases where the catalyst is itself a solvent for the reactants, no other solvent is necessary. Preferred inert organic solvents, when employed, are the non-polar type, among which may be mentioned hydrocarbons such as benzene, toluene and the like, and substituted hydrocarbons such as disulfide, chloroform, chlorobenzene, nitrobenzene, dichloroethylene, and the like.

Time and temperature of reaction are not critical. Thus, reaction may be efiected at from about 0. C. to C. or higher for from about 30 minutes to 24 hours, the exact duration and temperature depending on the choice of reactants, catalyst and solvent. Room temperature for several hours are the preferred reaction conditions.

The catalyst may be characterized as a Lewis acid of the type commonly known as Friedel-Crafts catalysts. These are generally halides of aluminum, tin, antimony, zinc, and gallium, including the anhydrous forms of these compounds. Among this known class of catalysts may be mentioned SnCl ZnCl AlCl SbCl GaCl and the corresponding bromides. The weaker catalysts are preferred, e.g., stannic chloride, SnCl It is thought that the catalyst operates to loosen or break the carbon-halogen bond in the aroyl reactant, making the latter reagent more electrophilic and therefore a more effective attacking reagent for the furan or thiophene starting material. However, this consideration of mechanism is not to be construed as a limitation on the instant invention.

Conventional separation and purification procedures are employed to isolate product (I) and include filtration, evaporation, solvent extraction, crystallization, and the like.

The procedures defined above may be run at atmospheric, subat-mospheric or superatmospheric pressure. Likewise, the procedures may be batch, semi-continuous or continuous and the sequence of addition of the reactants to one another is not critical.

The instant compounds are useful as starting materials in the preparation of some of the novel photochromic cycl-ohexadiene compounds of copending case Ser. No. 418,337, filed on the same day and incorporated herein by reference.

4 Analysis: Calcd for C H OS: C, 80.46; H, 4.91; S, 9.76. Found: C, 80.09; H, 5.22; S, 10.02.

EXAMPLES 3-20 Table I below summarizes reaction conditions for the preparation of other illustrative compounds of this invention, said preparations being substantially in accordance with those of Examples 1 and 2.

appended claims.

TABLE I Y R1 R4 Catalyst Solvent Tgrrp 5 CzHs O -CaH5N (Cgfifiz O-CaH-iSCzHs C] such Dichloroethylene 20 7-0 C3117 O m CBH-i 3 D-CBELNOZ C1 $11014 CS2 46 6-Br O p CsHiiCl O-CaI'IqOH Cl AlCla 46 6-OF3 0 IJ-CBHqOCHQ m-CaH4ON C1 sbcu 25 4-CsH5 S 0-CeH SCHa O-CaH C2H5 Br ZDBI: 120 4-CN s o CBHACN O-CBHJCFK C1 GaCl 50 5-NO2 S m-CaHiCHa m-CEH4N(C2H5)Z Cl such 25 6-SCH3 S 0-C3H4N0z m-CsILrBr 131 Such 0 7-C5H4CH3 s m-CEH4OH D'C6H4OCH3 Cl SnCh 5 6- H o D-CEEHNOQ CeHs Br AlBrz 10 6-N(CH3)1 O C3H5 p-CGH4NO2 C1 GaBra 50 6-CN S p-CeH4N (CH3): CsHs Cl such H O p-C5H4N (CH3); CsHs C1 S1101; 10 H o p-CBILCN CGHE; Br such 10 H S Cu 5 p-CaH4N(CH3)z C! 81101; 25 H S CaHs p-CaHsCN C1 811014 40 6-N(CH3)2 O C5115 CqHs C1 S1101; 25 6-CN S 06115 06H: Cl SnCli Nitrobenzene 25 EXAMPLE 1 We claim: 3O Preparatlon of 3-benz0yI-2-benzylbenzo[b]faran A compound of the formula Such ooonr +CGH5C 0 C1 \O/ CH206H5 \O/ OH2CuH A solution of 17.0 grams (0.082 mole) of Z-benzylbenzo[b]furan and 12.7 grams of benzoyl chloride (0.090 mole) in 50 ml. of carbon disulfide was swirled in a suit- (I) able reaction vessel disposed in an ice bath while 9.6 40

ml. (21.5 grams, 0.082 mole) of stannic chloride was added in portions during 5 minutes. After 18 hours at room temperature the mixture was concentrated under a stream of nitrogen and the resulting black tar was taken up in chloroform. The solution was washed twice with cold 6 N HCl and then twice with 5% sodium carbonate and dried over sodium sulfate. The dark oil resulting from evaporation was crystallized from etherpetroleum ether in several crops to give a total of 6.30 grams, M.P. 106-110" C. (25% yield). The analytical sample was recrystallized from ether; M.P. 110-111 C.

Analysis: Calcd for C H O C, 84.59; H, 5.16. Found: C, 84.36; H, 5.30.

EXAMPLE 2 Preparation of 3-benz0yl-2-benzylbenzo[b]thiophene To a solution of 9.1 grams of 2-benzylbenzo[b]thiophene (0.041 mole) and 7.0 grams of benzoyl chloride (0.050 mole) in 150 ml. of benzene in a suitable reaction vessel was added 5.8 m1. (0.050 mole) of stannic chloride. After two days at room temperature, crushed ice was added followed by 6 N I-ICl. The mixture was shaken occasionally until it reached room temperature and then heated on a steam bath with shaking for a few minutes. The organic layer was separated and washed with 6 N HCl and then twice with 5% sodium carbonate. The dried solution was evaporated to an acid which was chromatographed twice, using a column packed with neutral alumina, by eluting with ether. The resulting oil was finally crystallized from petroleum ether to give 0.9 gram (7% yield) of pale yellow crystals, M.P. 79-81 C.

wherein Q is selected from the group consisting of oxygen and sulfur and R and R are selected from the group consisting of phenyl and mono-substituted phenyl, said substituents for phenyl being selected from the group consisting of lower alkyl, lower alkyl thio, cyano, nitro, di(lower alkyl)amino, halogen and trifluorornethyl, and Y is selected from the group consisting of hydrogen, hydroxy, lower alkyl, trifiuoromethyl, lower alkoxy, lower alkyl thio, cyano, nitro, halogen, di(lower alkyl)amino, phenyl and lower alkyl-substituted phenyl.

2. 3-benzoyl-2-benzylbenzo[b]furan.

3. 3-benzoyl-2-benzylbenzo[b]thiophene.

4. 3 benzoyl 2-=(p-dimethylaminobenzyl)benzo[b] furan.

5. 3-benzoyl-2-(p-cyanobenzyl)benzo-[b]furan.

6. 2 p dirnethylaminobenzyl)-3 benzoylbenzo[b] thiophene.

7. 2-benzyl-3- (p-cyanobenzoyl benzo [b thiophene.

8. 6-dimethylamino-2-benzyl-3-benzoylbenzo[b]furan.

9. 6-cyano-2-benzyl-3-benzoylbenzo[b]thiophene.

References Cited UNITED STATES PATENTS 3,012,042 12/ 1961 Buu Hoi et a1 260-3462 FOREIGN PATENTS 1,076,702 3/ 1960 Germany.

OTHER REFERENCES Williams, Detoxication Mechanisms (1957), p. 194 relied on. Hartough, Thiophene and its Derivatives (1952), pp. 322 and 325.

WALTER A MODANCE, Primary Examiner. CECELIA SHURKQ, Assistant Examiner. 

1. A COMPOUND OF THE FORMULA 